If a person assumed their clothes were tahir (pure) but after prayer they realized it was not, what is the ruling on their prayer?
If the person assumed that the clothes were pure (because there was no reason to suspect impurity) and only found out that there was najasah on them after the prayers, then the prayers are valid. If a person doubts whether their clothing is tahir (pure) or not, they should check. If after checking, the clothes appear pure, however, after completing the prayer they actually discover that it was not, then their prayer is considered correct. However, if they did not check after doubting the purity of their clothing, and it turned out to be impure, then the prayer must be repeated based on obligatory precaution.